1

Fourth Quarter | 2019

Investor Presentation

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Statements in this presentation regarding management’s future expectations, beliefs, intentions, goals, strategies, plans or prospects, including, withoutlimitation, the statements relating to Mimecast’s future financial performance on both a GAAP and non-GAAP basis, may constitute forward-looking statementswithin the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements, other than statements of historicalfact, are statements that could be deemed forward-looking statements, including statements containing the words "predicts," "plan," "expects," "anticipates,""believes," "goal," "target," "estimate," "potential," "may," "might," "could," "see," "seek," "forecast," and similar words. Mimecast intends all such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 21E of the Exchange Act and the PrivateSecurities Litigation Reform Act of 1995. Such forward-looking statements involve known and unknown risks, uncertainties and other factors including thoserisks, uncertainties and factors detailed in Mimecast’s filings with the Securities and Exchange Commission. As a result of such risks, uncertainties and factors,Mimecast’s actual results may differ materially from any future results, performance or achievements discussed in or implied by the forward-looking statementscontained herein. Mimecast is providing the information in this presentation as of this date and assumes no obligations to update the information included inthis press release or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

In addition to GAAP financials, this presentation includes certain non-GAAP financial measures. These non-GAAP financial measures are in addition to, and not asubstitute for or superior to, measures of financial performance prepared in accordance with GAAP. Information regarding the non-GAAP financial measuresreferenced in this presentation, including the reconciliation to the nearest GAAP financial measures, can be found in the Appendix to this presentation. Pleaseconsider this as you review these non-GAAP financial measures.

This presentation contains statistical data that we obtained from industry publications and reports generated by third parties. Although we believe that thepublications and reports are reliable, we have not independently verified this statistical data.

The trademarks included herein are the property of the owners thereof and are used for reference purposes only. Such use should not be construed as anendorsement of the products or services of Mimecast.

This document may not be, reproduced or distributed, in whole or in part, by any means (including electronic without the prior written consent of Mimecast.

Safe Harbor for Forward-Looking Statements

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Peter Bauer Co-Founder, Chairman and CEO

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1. Unique technology platform

2. Large market opportunity

3. Favorable market drivers

4. Predictable business model

5. Strong track record

Mimecast Investment Highlights

Yearly Revenue

($ millions)$142

$187

$262

$340

2016 2017 2018 2019

Note: CAGR calculated on actual FX rates.

5

IPO November 2015

6

Accomplishments Since IPO Q4’16 – Q4’191

09

%

11

0%

11

1%

11

2%

11

1%

11

1%

11

1%

11

1%

11

0%

11

0%

11

0%

11

0%

11

1%

REV ENUE RETENTION RA TE

1,8

00

1,9

00

1,9

00

3,1

00

1,5

00

90

0

90

0 1,1

00

1,2

00

90

0

90

0

1,0

00

1,1

00

CUSTOMERS A D D S

44%

56%

Pre-IPO Since IPO

34,400 Total Customers

TTP Impersonation Protect

TTP Insider Protect

Sync and Recover

Mimecast AT

Mimecast Web Security

0

5,000

10,000

15,000

20,000

25,000

Q4

'16

Q1

'17

Q2

'17

Q3

'17

Q4

'17

Q1

'18

Q2

'18

Q3

'18

Q4

'18

Q1

'19

Q2

'19

Q3

'19

Q'4

19

29

% 32

% 38

%

39

% 45

%

43

%

41

%

36

%

33

%

31

%

32

%

33

%

32

%GROWTH RA TE CC

23,100 TTP CUSTOMERS

Financial Performance Customer Growth Products Introductions

77

Tech Platform

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Cloud Native Architecture

1. Multi-tenant

2. Multi-product

3. Microservices

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Mimecast’s Architectureis Unique SINGLE

INTEGRATED CODE BASE

DISPARATE CODE BASE PER PRODUCT

CORE SINGLE TENANT CORE MULTI TENANT

• Richer, better integrated

solution for customers

• Scales better operationally

for massive mid-market

• Strong leverage in our

business model

10

Scalable Infrastructure

Data as of December 31, 2018

• 12 data centers /6 locations

• 527 million emails delivered daily

• 296 billion emails managed

• Real-time threat intelligence

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Discrete Product Introduction and Adoption3

3,5

00

19

,70

0

14

,50

0

5,5

00

3,3

00

23

,10

0

4,9

00

2,5

00

80

0

Security Continuity Archiving Archive Add-Ons

Large FileSending

Targeted ThreatProtection

SecureMessaging

Internal EmailProtection

AwarenessTraining

.

2004 - 2005 2010 2013 2014 2015

Q4 FY19 Customers Rounded to the Nearest 100

2017 2018

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Targeted Threat Security, URL Protect,Attachment Protect, Impersonation Protect

Compliance Security, Data Loss Protection,Document Services

Email Continuity with 58 day retention

Email Archiving with 99 year retention

Products are Modular or Bundled

Add Ons: LFS, SM, IEP, APT Bundle Bundle

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• Protecting Employees and Data

• Shielding Infrastructure

• D-Dos, Spam, Malware, DLP

• Message routing and tracking

Core Email Security

Inbound

Outbound

14

TargetedThreatProtection (TTP)

TTP – URL Protect

with URL rewriting and dynamic user awareness

TTP – Attachment Protect

with file transcription, on-demand and pre-emptive sandboxing

TTP – Impersonation Protect

with dedicated detection of whaling and malware-less phishing

TTP – Internal Email Protect

with detection of lateral movements of attacksfrom one internal user to another

• A significant risk vector

• Spear-phishing

• Ransomware

• Whaling

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Email Continuity

• Reduces the impact of downtime

• Protects during:

• Tech Failure

• Security Incident

• Maintenance

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Multipurpose Data Archive

• Long term data preservation

• Storage Management

• E-discovery and Compliance

• Employee Productivity

1717

Market Drivers

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Growing Cybersecurity Threats

Risk

Mission critical 20192000

Data Employees Infrastructure

hackmalware

breach

phishing

spam

downtime

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Point Solutions vs Suites

• Single pane of glass

• Best of breed functionality

• Easy to deploy and manage

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IT Moving to the Cloud2015

Market Adoption of Office 365

Business Impact of Breach / Outage

100%

• Cloud Security responds faster and is

cheaper

• Office 365® drives demand for Cloud

Security, Archive, Continuity

• Highly concentrated single vendor

vulnerability risk

2121

Large Market Opportunity

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Total Addressable Market (TAM): $20 Billion

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Substantial Mid Market Opportunity

Source: 451 Research, March 2015 | Note: Middle Market (10-499 employees)Source: The Radicati Group, April 2015

Source: U.S. Small Business Administration, Office of Advocacy based on data provided by the U.S. Census Bureau, Statistics of U.S. Businesses (2011)

• SMB market under attack

• Limited IT resources

• Rapidly adopting cloud

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Strong Mid-Market Franchise

5,000+

100 - 5000

1-99

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World-Class Management Team

Rafe Brown

Chief Financial Officer

Ed Jennings

Chief Operating Officer

John Walsh

SVP Engineering & Technical Operations

Joined Mimecast in 2019

Previously CFO and head of services and support at

SevOne, CFO & CAO at Pegasystems Inc.. SVP of Finance at Salesforce.com

Joined Mimecast in 2015

Previously CMO at application security company, Veracode and General Manager at ADP

responsible for their SaaS-based compliance business

Joined Mimecast in 2017

Previously held SVP of Engineering and CTO roles at Constant Contact, CareCloud,

Tremor Video and Avid.

Peter Bauer

Chief Executive Officer

Co-founded Mimecast in 2003.

Previously Founded FAB Technology, and worked as a Microsoft systems engineer specializing in corporate

messaging systems

Bob Nault

General Counsel

Joined Mimecast in 2016

Previously, SVP, General Counsel, at Constant Contact. Led the legal team though tremendous growth, IPO and several acquisitions. SVP,

General Counsel, RSA Security

Janet Levesque

SVP Systems, Risk& Security

Joined Mimecast in 2017

Previously Chief Information Security Officer at RSA the

security division of Dell/EMC

Christina Van Houten

Chief Strategy Officer

Joined Mimecast in 2018

Previously held leadership roles at Oracle, IBM, Infor

Global Solutions, Netezza and ProfitLogic

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Business Model

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Financial Highlights

On average customers have 3.1 services

98% Recurring Revenue

Revenue Retention Rate 111%

Demonstrated Profitability

34% RevenueCAGR FY16-19

24% Customer growthCAGR FY16-19

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Revenue GrowthYearly Revenue

($ millions)

Quarterly Revenue

($ millions)

$142

$187

$262

$340

2016 2017 2018 2019

$37$41

$44$48

$52$58

$63 $67

$73 $78

$82 $88

$92

Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

2016 2019Note: CAGR calculated on actual FX rates.

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Highly Diverse Revenue BaseGeographic DiversityVertical Market Diversity

Note: Q4 FY2019 ended March 31, 2019

Professional Services14%

Finance and Insurance

14%

Legal Services11%

Manufacturing11%

Health Care8%

Construction6%

Government6%

Retail6%

Transportation 4%

Information4%

Real Estate 3%

Other13%

United States

50%

UK & Europe32%

Africa13%

Rest of World5%

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Growing Customer Base With Multiple Services

Multiple services benefit customers

Customers and services they use Q4 2019

Customers (thousands)

15

%

38

%

27

%

20

%

31 2 4+

Number of services per customer Q4 2019

18

26.4

30.4

34.4

FY16 FY17 FY18 FY19

33

,50

0

23

,10

0

19

,70

0

14

,50

0

5,5

00

4,9

00

3,3

00

2,5

00

80

0

Secu

rity

TTP

Co

nti

nu

ity

Arc

hiv

ing

PT

SM LFS

IEP

AT

31

How We Sell

SMB and

MSPs

Channel Strategy

Frictionless High Velocity

Inside Sales

Larger Customer Coverage

National Partners

Channel Heavy

Direct & Channel

Leverage SIs

SalesStrategy

SaaS Fundamentals

5,000+

Employees

100-5,000

Employees

1-99

Employees10%

73%

17%

% of RevenueQ4 2019

ScalableEase of IntegrationSaaS ModelSubscription paymentAnnual Contracts Modular Product Offerings

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Gross Margin

Adjusted EBITDA margin

70%

73%

72%

73%

74% 74% 74% 74%

73% 73% 73% 73% 73%

Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

1.3%

4.5%

6.2%7.6% 6.8%

8.8%10.5% 10.0% 9.8%

12.7%15.0%

18.2% 17.1%

Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

20192016

2016 2019

• Attractive Financial Profile

• Investing In Growth

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Significant Upsell Potential

2019 Revenue Retention Rate Annual Revenue Retention Rate

109%

111%

110%

111%

FY16 FY17 FY18 FY19

100%

(6%)

16% 111%

Note: Rounded to the nearest percent

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FY16 FY17 FY18 FY19 Long-term

Gross Margin 71% 73% 73% 73% 72-75%

R&D % Rev. 12% 12% 15% 17%

S&M % Rev. 46% 52% 46% 41%

G&A % Rev. 14% 15% 14% 15%

Adj. EBITDA 11% 6% 10% 16% 20-22%

Note: Fiscal Year Ends March 31

Long-term Target Model

3-5 years from IPO at$350-$450 mill in revenue

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Q4 FY 2019 Highlights

1,100 net new customers in Q4 34,400 total customers

Revenue retention rate 111%Constant currency revenue growth of 32% YoY to $92.2m

Gross profit 73%

Positive adjusted EBITDA of $15.8 million

Note: FY2019 ended March 31, 2019

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Fourth Quarter | 2019

Investor Presentation