How to search IMAP in .NET

One of many advantages IMAP protocol has over POP3 protocol is the ability to search. IMAP search is done entirely on server side, which means that it’s fast and does not require Mail.dll to download much data over the network.

There are several ways of performing search using Mail.dll IMAP library:

SearchFlag – for common flag searches (seen, unseen, …).
SimpleImapQuery – easy one object query, where all conditions are joined with AND operator.
Expression syntax – most advanced, allows using AND and OR operators and sorting.

Let’s start with the basics: we’ll connect to the IMAP server and login:

// C# code:

using (Imap imap = new Imap())
{
    imap.Connect("imap.example.com");        // or ConnectSSL for SSL
    imap.Login("user", "password");
    imap.SelectInbox();

    // Search code goes here

    imap.Close();
}

' VB.NET code:

Using imap As New Imap()
    imap.Connect("imap.example.com")        ' or ConnectSSL for SSL
    imap.Login("user", "password")
    imap.SelectInbox()

    ' Search code here

    imap.Close()
End Using

SearchFlag

Now the first and the simplest way using Imap.SearchFlag method. The sample finds all unseen email messages (those that have \UNSEEN flag).

// C#

List<long> uidList = imap.SearchFlag(Flag.Unseen);

// now download each message and display the subject
foreach (long uid in uidList)
{
    IMail message = new MailBuilder()
        .CreateFromEml(imap.GetMessageByUID(uid));
    Console.WriteLine(message.Subject);
}

' VB.NET

Dim uidList As List(Of Long) = imap.SearchFlag(Flag.Unseen)

' now download each message and display the subject
For Each uid As Long In uidList
	Dim message As IMail = New MailBuilder()_
		.CreateFromEml(imap.GetMessageByUID(uid))
	Console.WriteLine(message.Subject)
Next

SimpleImapQuery

Second approach is to use the IMAP query object. The sample below searches for all unseen emails with certain subject.

// C#

SimpleImapQuery query = new SimpleImapQuery();
query.Subject = "subject to search";
query.Unseen = true;

List<long> uids = imap.Search(query);

' VB.NET

Dim query As New SimpleImapQuery()
query.Subject = "subject to search"
query.Unseen = True

Dim uids As List(Of Long) = imap.Search(query)

Expression syntax

Finally most advanced search option using Expression class. You can use AND, OR and NOT operators in your IMAP search:

// C#

List<long> uids = imap.Search().Where(
    Expression.And(
        Expression.Not(Expression.Subject("subject not to search")),
        Expression.HasFlag(Flag.Unseen)));

' VB.NET

Dim uids As List(Of Long) = imap.Search().Where(_
    Expression.[And](_
        Expression.[Not](Expression.Subject("subject not to search")),_
        Expression.HasFlag(Flag.Unseen)))

Expression syntax with sorting

Expression search syntax also allows sorting. This feature is not available for every IMAP server. You need to check if your IMAP server supports ImapExtension.Sort extension.

// C#

List<long> uids = imap.Search()
    .Where(Expression.And(
            Expression.Not(Expression.Subject("subject not to search")),
            Expression.HasFlag(Flag.Unseen)))
    .Sort(SortBy.Multiple(
            SortBy.Date(),
            SortBy.Subject()));

' VB.NET

Dim uids As List(Of Long) = imap.Search() _
    .Where(Expression.[And]( _
        Expression.[Not](Expression.Subject("subject not to search")), _
        Expression.HasFlag(Flag.Unseen))) _
    .Sort(SortBy.Multiple( _
        SortBy.[Date](), _
        SortBy.Subject()))
)

Notice the neat trick in Mail.dll that allows casting FluentSearch class received from imap.Search() method to List<longs>

public static implicit operator List<long>(FluentSearch search)
{
        return search.GetList();
}

We tend to use it very often for builder objects used in unit testing.

If you like it just give it a try and download it at: Mail.dll .NET IMAP component

Tags: C#, IMAP, Mail.dll, VB.NET

This entry was posted on Wednesday, November 25th, 2009 at 20:03 and is filed under Component. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

27 Responses to “How to search IMAP in .NET”

Gene Says:
March 30th, 2010 at 14:29
Can you search by message id? I see you have a header option to search by but not sure how to use it.

Limilabs support Says:
March 30th, 2010 at 15:31

Yes, you can search by message-id header:

List<long> uids =  imap.Search(
     Expression.Header("Message-ID", "<message@id.com>"));

Gene Says:
March 30th, 2010 at 17:52
Worked perfect!!
Peter Gordon Says:
February 9th, 2011 at 00:24
Can you search the Body? I tried Expression.Body(text to search for) but I get an unhandled error.
Limilabs support Says:
February 9th, 2011 at 01:13
@Peter
Yes, you can search the body:

List uids = imap.Search(Expression.Body(“19812345″));

What kind of exception are you getting?
What is the message?
What is the stack trace?
Can you prepare a log file (http://www.limilabs.com/blog/logging-in-mail-dll)?
What server are you using?
Are you using any special characters?
Peter Gordon Says:
February 9th, 2011 at 01:20
I am using Windows Server 2008 R2, IIS 7.5 with .Net 4.0 (c#).

I can prepare a log file tomorrow morning – the only message I got was an unhandled error as i did not have logging turned on.

I am passing a string with standard HTML formatting to search on so likely I do have some special characters in the string (it is pretty long). I can test with a simpler string in the morning as well.
Limilabs support Says:
February 9th, 2011 at 15:35
@Peter
You said you are using pretty long strings.
Most likely the problem is with CR LF characters.
Currently you can not use those characters in searches. Sorry.
We’ll try to address this issue in next release.
Peter Gordon Says:
February 9th, 2011 at 15:42
Good Morning,

It seems like the Expression.Body statement error’s out when the string for the search criteria includes an apostrophe. There may be other characters as well.

It work’s fine when I pass a short string with only alpha characters. [...]
Limilabs support Says:
February 9th, 2011 at 16:51
@Peter
Unfortunatelly this is a Gmail bug. There is nothing we can do about it.
Gmail has very similar problem with national characters.
Peter Gordon Says:
February 9th, 2011 at 19:18
No worries Paul – I can work around this requirement (it is likely better not to search on the Body text anyway for the purposes that I was considering doing it).

Thanks for your help.
Limilabs support Says:
February 22nd, 2011 at 18:27
Mail.dll was updated today and now supports any characters in the search, including CR LF.

Mail.dll now uses a bit different IMAP server communication model and we have been able to workaround this Gmail bug. From now on national characters should work correct in Gmail searches
Ben Says:
April 20th, 2011 at 21:56
I want to only retrieve a list of emails via IMAP in date range specified (based on the date the email was sent). I have done quite a lot of searching on this site and online and can’t find an example for how to do this. Does anyone have a sample to get me started or even point me to the method or class that I should be using to do this?
Limilabs support Says:
April 21st, 2011 at 12:19
Ben,

~~Unfortunately IMAP protocol does not have such feature.)~~

~~What can you do is to use Imap.GetEnvelope or GetMessageInfo methods to download informations about all emails (it’s relatively fast) as described here:~~
http://www.limilabs.com/blog/get-email-information-from-imap-fast

~~Envelope has a Date field that you can use (it corresponds to email’s Date header~~
(See Ben comment below)
Ben Says:
April 29th, 2011 at 23:35
Hmmm…

I spent a couple of days now looking at this and unfortunately, I believe you are incorrect. When I do this code with imap:

DateTime dateBegin = DateTime.Now.AddDays(-30);
List listOfUids = imap.Search(Expression.SentSince(dateBegin);

This works and returns back the correct number of Uid’s within that range and is still very quick.

Maybe I asked my question incorrectly?
Limilabs support Says:
May 1st, 2011 at 12:19
@Ben,

You are correct.
I totally forgot about Expression.Since and Expression.SentSince.
Kris Says:
August 18th, 2011 at 16:49
I’m trying a filter criteria based on the Subject as well as From address with an Expression.OR condition and it always returns only 160 results…Is there a limitation with the trial version?
Limilabs support Says:
August 18th, 2011 at 20:11
@Kris

Most likley you are using Yahoo as your email provider.

It seems Yahoo is limiting the search result (for queries that search subject, body) to the newest 160 records.

It also seems that there is no way to get to the previous records using IMAP search.

It’s definitively Yahoo bug, and currently I don’t see a way to workaround it.
Knut Bøhn Says:
September 15th, 2011 at 14:24
Is it possible to nest multiple or expressions, to add more from-criteria to something like
```
List<long> uidList = imap.Search().Where(
	Expression.And(
		Expression.SentSince(DateTime.Parse("01.09.2011")),
		Expression.Or(
			Expression.From("a.com"),
			Expression.From("b.com")
		) // or
	) // and
); // where
```
?
in other words: where sentsince>20110901 && (from ==”a.com” || from ==”b.com”|| from ==”c.com”) etc etc

Thanks,
knut
Limilabs support Says:
September 15th, 2011 at 20:54
@Knut

Yes, it should work exactly like you put it (I just applied some formatting).
Knut Bøhn Says:
September 16th, 2011 at 10:30
Guess I’m getting lost in all the brackets… – I need to put an Expression.Or first?
Limilabs support Says:
September 17th, 2011 at 08:54
Knut,

The expression you provided works exactlly like you want:
sentsince>2011/09/01 && (from == “a.com” || from == “b.com”)
Gonzo Says:
November 6th, 2011 at 12:33
When I search for Expression.From(“first name last name”) – it finds the mail.

When I search for Expression.From(“name@domain.com”) – it does not find the mail.

So, it appears to only search the display name of the from text, not the from email address.

Is there any way to search for the from email address?
Limilabs support Says:
November 8th, 2011 at 14:54
@Gonzo

The search is done entirely on the server side.
If the server implements search functionality incorrectly there is not much we can do.

Could you prepare a log file for us, so we can make sure that Mail.dll generates correct search query?
Louie Says:
December 2nd, 2011 at 07:53
hi,

I am a web developer who is trying to implement a web mail as a part of the project that i am working on. it requires synchronous the local cache and imap server. would you please let me know how would I search mailbox by uid? (i need to search uid greater than a certain value) so that i can only download the email from server which haven’t been downloaded yet.

many thanks

best regards

Louie
Limilabs support Says:
December 2nd, 2011 at 13:04
@Louie

You can use Expression.UID method.
It allows you to select a range of uids you are interested in.

To search uids greater that a certain value:
```
List<long> uids = client.Search().Where(Expression.UID(Range.From(55)));
```
To search uids in specified range (from 55 included to 135 included):
```
List<long> uids = client.Search().Where(Expression.UID(Range.Create(55, 135)));
```
Louie Says:
December 5th, 2011 at 04:19
hi

I have just tried to client.Search().Where(Expression.UID(Range.From(100))); it still return me the email with biggest uid on server (25). however, when i use rang.creat(26,100), it give me the correct result (no emails found).
Limilabs support Says:
December 6th, 2011 at 21:13
@Louie,

I’m afraid that this may be a server bug (the search is done entirely on the IMAP server side).

How to search IMAP in .NET

SearchFlag

SimpleImapQuery

Expression syntax

Expression syntax with sorting

27 Responses to “How to search IMAP in .NET”

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